1. Field of the Invention
The present invention relates to a method of producing a piezoelectric device adapted to be installed in an oscillation circuit, a filter circuit or the like.
2. Description of Related Art
Conventional piezoelectric devices are categorized into two types, depending on the way they are structured. One type is wherein a piezoelectric transducer is placed between protection boards so as to have a space for vibration. The other type is wherein a piezoelectric transducer is shielded in a protection case so as to have a space for vibration. Generally, a crystal plate, a ceramic plate or a metal plate having a piezoelectric layer thereon is used as the piezoelectric transducer. The protection boards and the protection case are made of resin, metal, ceramics or the like.
The vibration frequency and resonance characteristic of such a conventional piezoelectric device cannot be adjusted after the piezoelectric transducer is encased in the protection case or the protection boards. If the vibration frequency is found to be incorrect in a product checking process, it is too late to make a correction.
The piezoelectric transducer is usually connected with the protection boards or the protection case by adhesive. In the case of a device with the transducer encased in a protection case, an electrode extended from a vibrating electrode of the piezoelectric transducer may be joined to a conductor disposed on an inner wall of the protection case by conductive adhesive. Generally, thermosetting resin like epoxy resin is used as the adhesive. In order to harden such resin, the piezoelectric device must be processed under a high temperature (about 150.degree. C.). If temperature control in this process is not carried out carefully, the polarization of the piezoelectric transducer will be impaired by heat, thereby failing to provide a designed electric characteristic.